"The food you eat can be either the safest and most powerful form of medicine or the slowest form of poison." Ann Wigmore
The Mediterranean diet has long been quoted for its health benefits. The traditional food of Greece, Southern Italy and Spain is well known for an abundance of plant-based foods like fruit, vegetables, whole grain cereals, nuts and legumes; moderate in fish, poultry, eggs and red wine (consumed with meals) and low in dairy products, red meat, processed meats, and sweets.
A number of well-designed randomised controlled trials have been consistently showing that the Mediterranean diet enriched with extra-virgin olive oil and nuts has a powerful impact on our general health reducing the risk of cardiovascular disease, diabetes, obesity, metabolic syndrome and breast cancer.
One of the major and most influential medical trials, the Spanish PREDIMET study, enroled almost 7,450 people at high risk of cardiovascular disease, looking at a link between a particular diet and the risk of heart attack, stroke, and death from cardiovascular causes. All participants were advised to implement one of the three following diets: the Mediterranean diet supplemented with extra-virgin olive oil, the diet supplemented with mixed nuts, and the control diet with reduced dietary fat.
Although the study had some limitations and losses in the follow-up group, the results were unequivocal. People who followed the Mediterranean diet supported with extra-virgin olive oil and nuts were at significantly lower risk of major cardiovascular events.
In the same study, researchers found that during almost five-year follow-up, nut consumption was related to a significantly lower cardiovascular risk and cancer mortality. People eating nuts (more than three servings a week) had a lower risk of death than those who didn't consume nuts at all.
Does the Mediterranean diet lower the risk of type 2 diabetes?
An updated version of the PREDIMET study, published a few years ago, was looking at how the Mediterranean diet might be associated with type 2 diabetes. The study enroled more than 400 people with no diabetes for four years. The participants were divided into two groups; the first group was advised to add either virgin olive oil or nuts to their daily diet, the second group followed a basic low-fat diet.
The study found that the traditional Mediterranean diet with added virgin olive oil or mixed nuts decreased the risk of type 2 diabetes by 51% in people at high cardiovascular risk, compared to a control group. It’s important to mention that the significant reduction in the risk of diabetes occurred despite the absence of major changes in weight or physical activity.
Does the Mediterranean help prevent chronic conditions?
To answer the question we need to look at people with so-called metabolic syndrome - a combination of risk factors for cardiovascular disease such as high blood pressure, abdominal obesity, abnormal levels of blood cholesterol (dyslipidaemia), and high blood sugar (hyperglycaemia).
The largest multi-centre clinical trial enroled more than 1,200 people to look at the potential influence the Mediterranean diet might be having on people with metabolic syndrome. All participants, at high risk of cardiovascular disease, were divided into three groups to implement either a virgin olive oil diet or a mixed nuts diet or a control group with a low-fat diet. After one year of intervention, the risk of metabolic syndrome was reduced by 6.7%, in the group with olive oil, by 13,7% in the group with nuts and by 2% in the control group.
Other dietary interventions were looking at how the Mediterranean diet might be associated with weight loss. The most recent study enroled more than 320 obese participants to follow a calorie restricted low-fat diet or a calorie restricted Mediterranean diet, or an unrestricted low-carb diet.
In result of the two-year programme, patients with type 2 diabetes on the Mediterranean diet lost weight and had lower levels of both blood glucose and insulin, compared to those on the low-fat diet. People following the low-fat group lost 2.9 kg (6.4 lbs); those who followed the low-carb lost 4.7 kg (10.3 lbs), and the Mediterranean diet group lost 4.4 kg (9.7 lbs). Researchers concluded that the Mediterranean diet is more effective for weight loss and improving symptoms of type 2 diabetes than the low-fat diet.
Does the Mediterranean diet help us live longer?
Researchers at Harvard Medical School involved more than 4,650 healthy women, whose diet was similar to the ideal Mediterranean diet to look at the link between the diet and the length of telomerase - the protective structures at the end of chromosomes. A rule of thumb: the longer the telomeres, the healthier we are and the longer we live. Shorter telomeres are linked to a higher risk of developing chronic conditions and a lower life expectancy.
The scientists measured the telomere lengths and followed the group for more than twenty years with periodic examinations. The study concluded that the change in the adherence score they measured was equal to 4.5 years of ageing.
So, why is that? It turns out that the Mediterranean diet has the power to normalise and even increase so-called mitochondrial respiratory chain, as well as other mitochondrial activities which through complex interactions lead to DNA synthesis and repair, and consequently, to telomere length regulation.
The Mediterranean diet isn’t a magic prescription for a long life. In fact, there is no magic prescription, particularly when it comes to food. Some studies are just observational or include unrepresentative sample groups. What we know, however, is that having an evidence-based knowledge about food expands our self-awareness and the ability to make more conscious, tailor-made choices; the ones that result in living happier, healthier and more fulfilling life.